Anabolic and energetic signaling in human skeletal muscle in response to amino acids and endurance exercise

Abstract

Resistance exercise potentiates anabolic signaling in response to amino acids. However, endurance exercise may interfere with amino acid‐mediated anabolic signaling through activation of AMPK. Thus, we examined nutrient and energy sensing signaling pathways in response to amino acids and endurance exercise (AA+EE) in young (n=9) and older (n=8) men. Muscle biopsies were obtained at rest and again at 10 and 180 min of recovery from 45 min of walking at 40% VO2PEAK. AMPKα and ACC were unchanged in response to AA+EE. Although Akt, mTOR, and 4E‐BP1 appear unaltered by AA+EE, phosphorylation of the downstream effector p70S6K was significantly increased. Our data show, for the first time in humans, that AA+EE increases the phosphorylation of p70S6K, which is a key anabolic signaling protein.